1. Field of the Invention
The present invention relates to a heater, and more particularly, to a heater in which a material of the heating element is different from a material of the leads such that a location of a hot spot in the heater is controllable based on a polarity of current in the heater.
2. Description of the Related Art
The importance of nanoheaters and/or nanoscale thermal transducers for local heat delivery has been realized for magnetic thermal recording, ferroelectric thermal recording, phase-change recording and reading, and thermal memory (e.g., see U.S. Pat. Nos. 6,532,125, 6,233,206, 6,597,639 and 6,433,310, and U.S. Patent Publication No. US20040188668A1, all of which are commonly assigned to the present assignee and are incorporated by reference herein).
The importance of nanoheaters and/or nanoscale thermal transducers for local heat delivery has also been realized for thermo-mechanical storage applications (e.g., “Atomic force microscope cantilevers for combined thermomechanical data writing and reading”, W. P. King, T. W. Kenny, K. E. Goodson, G. Cross, M. Despont, U. Dürig, H. Rothuizen, G. K. Binnig, and P. Vettiger, Appl. Phys. Lett. 78, 1300 (2001)).
One of the key challenges in the use of nanoheaters and/or nanoscale thermal transducers for local heat delivery is the control of the location and the spatial extent of the resulting hot spot. More specifically, U.S. Patent Publication No. US20040188668A1, discloses a small nanoheater which is used to program a thermal and/or electrical impedance of a storage material, which is part of a memory cell. This small nanoheater provided some control of the location and the spatial extent of the resulting hot spot. However, it is desired to further improve such control.